A chain transmission device including a timing chain trained around a driving sprocket mounted to a crankshaft and a driven sprocket mounted to a camshaft and adapted to drive the camshaft further includes a pivotable chain guide provided on one side of the slack side of the timing chain, and a chain tensioner adapted to apply an adjusting force to the end of the chain guide remote from the end about which the chain guide pivots, thereby minimizing slackening and flapping of the timing chain by tensioning the chain.
Such a chain transmission device further includes a stationary chain guide fixedly mounted to extend along the tension side of the timing chain to guide the movement of the timing chain, thereby further reducing flapping of the chain.
Such known chain guides, which are used to adjust the tension of the timing chain or guide the movement of the timing chain, include those of the type that guides the timing chain by being in surface-to-surface sliding contact with the timing chain. This type of chain guide, however, has a problem in that a large moving resistance is applied to the timing chain, thus increasing loss of torque to be transmitted.
In order to avoid this problem, WO 2010/090139A proposes a chain guide which includes a guide base elongated in a moving direction of the timing chain, a plurality of roller shafts arranged along a curved line and having both ends thereof supported by the guide base, and rollers comprising roller bearings rotatably mounted on the respective roller shafts such that the timing chain is movably guided by the rollers.
In this chain guide, since the timing chain is guided by the rollers with the rollers in rolling contact with the timing chain, moving resistance applied to the timing chain is small, and so is the loss of torque to be transmitted, compared to when the timing chain is guided by surface-to-surface sliding contact.